what the hell is going on??

ca

so ive been getting cramps from hell during this cycle. my blood has been mostly brown. and when I went to the bathroom earlier, this showed up.

I braved up enough to touch it and found that it was folded in half, so it was twice as wide as in the picture. does anyone know what it is or what caused it? I'm on my 3rd cycle on a new birth control. it's not a miscarriage because I know I'm not pregnant.